Conventionally, a radar apparatus which detects an obstacle around a vehicle and calculates a track of movement of the obstacle relative to the vehicle, and a system which controls the vehicle on the basis of information of the track, have been developed.
For example, Patent Literature 1 discloses one example of the radar apparatus as described above. An obstacle recognition apparatus for a vehicle, which is disclosed in Patent Literature 1, irradiates the vicinity of the vehicle with a transmission wave such as laser light and receives a reflected wave of the transmission wave from an object, thereby detecting the object. Next, the obstacle recognition apparatus for the vehicle recognizes the detected object around the vehicle by a set of multiple points. Then, the obstacle recognition apparatus for the vehicle recognizes adjacent points out of the multiple points, as one segment. Then, the obstacle recognition apparatus for the vehicle recognizes the segment as a line segment having only a length in a width direction of the vehicle. In other words, the obstacle recognition apparatus for the vehicle recognizes the detected object as the line segment corresponding to the length of the object in a width direction of the object.
Here, the obstacle recognition apparatus for the vehicle, which is disclosed Patent Literature 1, can track the detected object. The obstacle recognition apparatus for the vehicle respectively compares the length and the position of a previously detected line segment to the length and the position of a currently detected line segment. Then, when the difference between the length of the previously detected line segment and the length of the currently detected line segment is within a predetermined range and the distance between the position of the previously detected line segment and the position of the currently detected line segment is within a predetermined range, the obstacle recognition apparatus for the vehicle determines that the previously detected object is identical to the currently detected object. By detecting the position of the object at each time in such processing, the obstacle recognition apparatus for the vehicle can track the detected object.
In a driving support system for a vehicle, which has been developed recently, a track obtained by tracking an object detected by a radar apparatus is calculated. Then, the driving support system infers a risk of collision of the vehicle with the object on the basis of the track and the like. In addition, the driving support system performs vehicle control in accordance with a result of the inference concerning the risk of collision. For example, when there is a risk of collision of the vehicle with the object, the driving support system performs a process of outputting an alarm which notifies a driver of the risk, or the like.    [Patent Literature 1] Japanese Laid-Open Patent Publication No. H7-318652